Headphone demonstration unit



FIG. 1 is a top perspective view from the front of the headphone demonstration unit, showing my new design;

FIG. 2 is an underside perspective view from the rear of the unit of FIG. 1, and

FIG. 3 is a section along the line 3--3 in FIG. 1. 

The ornamental design for a head phone demonstration unit, as shown. 